From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philip Langdale Subject: Re: [PATCH] sdio: add MMC_CAP_VDD_165_195 host capability Date: Mon, 12 Oct 2009 19:39:52 -0700 Message-ID: <20091012193952.1482e322@fido2.homeip.net> References: <1254160269.10634.15.camel@localhost> <4AC0FBF0.6090007@csr.com> <20090928192548.11da5c3c@fido2.homeip.net> <20090929202833.179fb521@mjolnir.ossman.eu> <20090929233732.62f470e0@mjolnir.ossman.eu> <20090929231013.5d67b36a@fido2.homeip.net> <20091008203826.5e027347@mjolnir.ossman.eu> <20091010114215.5f9d8c94@fido2.homeip.net> <4AD32B01.5000600@csr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from usul.overt.org ([204.11.33.43]:35857 "EHLO usul.overt.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755358AbZJMClD (ORCPT ); Mon, 12 Oct 2009 22:41:03 -0400 In-Reply-To: <4AD32B01.5000600@csr.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: David Vrabel Cc: Pierre Ossman , Ohad Ben-Cohen , akpm@linux-foundation.org, ian@mnementh.co.uk, matt@console-pimps.org, roberto.foglietta@gmail.com, linux-mmc@vger.kernel.org On Mon, 12 Oct 2009 14:11:29 +0100 David Vrabel wrote: > > In the 3.00 spec, OCR bit 24 is S18R (Signalling 1.8V request). This > is outside of the VDD region (bits 0:23). So I think we can support > non standard DS/HS (Default Speed/High Speed) cards that report 1.8V > operation (in the VDD region) and new UHS-I (Ultra High Speed phase I) > cards without any confusion. > > On a UHS-I capable controller, the software would send ACMD41 with > S18R set and see if the card responses with it set. If so, it tells > the card to switch to 1.8V signalling (CMD11) and tells the > controller to switch to 1.8V signalling and SDR12 mode. The > controller still supplies 3.3V to the card even after the switch. > Later on the host software will query the card to find out what UHS-I > modes are supported and switch card and controller to a faster mode > (if possible). Interesting. But that means that Ohad's patch doesn't make much sense; his uses the MMC low voltage OCR bit in an SDIO context. So either, the patch is wrong, or he's dealing with out-of-spec hardware. Ohad? --phil